The present invention relates to a file server, a file server log management program and a file server log management method.
In order to achieve the efficient management of large quantities of data, which are increasing day by day, file servers which manage numerous files, previously dispersed and managed by means of a plurality of computers, by gathering these files together in a single place have become popular. In particular, file servers of the type known as “NAS” (network attached storage) differ from file servers of the all-purpose type in which an all-purpose file server function is installed in an all-purpose computer in that NAS are designed especially as file servers. Accordingly, NAS show a high processing performance and reliability as file servers, and can be used comparatively easily immediately following introduction. Consequently, such systems are widely used.
In order to allow the accurate management of setting alterations in respective devices, and time when evens such as unauthorized intrusions and the like occur, NAS and network managers to which NAS are connected manage all of the log information in these respective devices in a concentrated manner in special servers called log management devices (Japanese Patent Application Laid-Open No. 8-263330).
However, if the authority of the manager of a log management device is used, log information stored in the log management device can be deleted, and the content can be rewritten. Accordingly, the log information stored in a log management device cannot be relied upon “as is”.
Consequently, for example, a system has also been proposed in which the log information recorded by devices installed on a network is respectively transmitted to a plurality of log management devices by using a syslog protocol (See “RFC3164—The BSD Syslog Protocol”, Requests for Comments (3164), by C. Lonvick, August 2001. As a result, the same log information can be redundantly managed in a plurality of log management devices having respectively different managers.
Generally, with the ease of management work and the like being taken into account, servers and log management devices, and the networks in which these servers and log management devices are installed, are comprehensively managed by the same manager. In this case, however, the manager himself can rewrite or delete log information. Accordingly, it is difficult to discover unauthorized behavior (behavior such as the modification of log information or the like) on the part of the manager himself, or unauthorized behavior on the part of a third party usurping the authority of the manager.
On the other hand, in cases where the same log information is respectively transmitted to a plurality of log management devices, and the respective log management devices are managed by different managers, the reliability is improved compared to cases in which the log information is managed in a single place.
Even in such cases, however, since the respective log management devices are installed on the same network, there is a danger that one of the respective managers, or a third party, may modify log information managed by some log management devices or the like using the fragility of other log management devices in terms of security.